1. Field of the Invention
The present invention relates to a cooling plate used for, for example, various temperature controlling cooling plates such as backing plates, susceptors for use in sputtering apparatuses, semiconductor manufacturing apparatuses or LCD manufacturing apparatuses.
In this specification, the language xe2x80x9caluminumxe2x80x9d denotes aluminum and its alloys.
2. Description of Related Art
For example, a sputtering apparatus for manufacturing semiconductors has a backing plate for holding a target. As shown in FIG. 6, the backing plate 101 is provided with a cooling medium passage 102 therein for cooling the target 100 attached to the surface of the backing plate. In detail, the backing plate 101 is comprised of two aluminum plates 103 and 104 joined in a stacked manner, and provided with a circuit-like cooling medium passage 102 therein formed by integrally joining aluminum plates 103 and 104 so as to coincide with cooling medium passage forming grooves each formed on the joining surface of the aluminum plate.
In a conventional baking plate, the joining of the two aluminum plates 103 and 104 is generally performed by brazing the joining surfaces to prevent the leakage of the cooling medium passing through the cooling medium passage 102.
However, in a conventional backing plate, since the aluminum surfaces of the grooves 105 and 106 are exposed as it is, these grooves corrode when water, etc., as a cooling medium passes through these grooves 105 and 106 for a certain time period. Thus, the life as a backing plate is relatively short. Because of the degradation by the corrosion, the backing plate should be replaced with new one within, e.g., one or two years.
The present invention is made in view of the aforementioned technical background, and aims to provide a high cooling performance cooling plate with a cooling medium passage which is excellent in corrosion resistance and long in life.
The aforementioned object can be attained by a cooling plate provided with a cooling medium passage therein, the cooling medium passage being formed by integrally joining a plurality of metal plates each having a cooling medium passage forming groove on a joining surface thereof, characterized in that: an anodic oxide film is formed on at least the cooling medium passage forming groove on the joining surface, and the plurality of metal plates are integrally joined each other by a friction agitation joining method.
With this cooling plate, since the anodic oxide film covers at least the cooling medium passage forming groove, the corrosion of the cooling medium passage can be effectively prevented, which dramatically enhances the durability of the cooling plate. Furthermore, since the joining of the metal plates is performed by a friction agitation joining method, the welded portion does not give bad influence such as degradation on the anodic oxide film. Accordingly, the excellent corrosion-prevention effect can be maintained effectively, resulting in a cooling plate excellent in durability and long in life. Furthermore, due to the friction agitation joining method, the metal plates can be joined in a good condition, which enables a uniform cooling.
It is preferable that the anodic oxide film is formed on an entire surface of the joining surface of the metal plate. This enables a corrosion prevention of not only the cooling medium passage but also the entire joined surfaces of the metal plates, which further improves the durability of the cooling plate.
It is preferable that at least the vicinity of the peripheral portion of the cooling medium passage in a gap between joined metal plates is fluid-tightly sealed with a sealing agent. This prevents the leaking of cooling medium such as water to portions other than the cooling medium passage and the stagnation of the cooling medium. Thus, the generation of corrosion at gaps can be prevented assuredly, which further improves the durability of the cooling plate.
From a viewpoint of joint durability, it is preferable that the sealing agent is metal material, or the sealing agent is waterproof resin adhesive.
It is preferable that the waterproof resin adhesive is one or more resin selected from a group consisting of epoxy family resin, phenol family resin and polyolefin family resin because these resin are excellent especially in joint durability.
An aluminum plate is preferably used as the metal plate. This results in a lightweight cooling plate.
According to a method for manufacturing a cooling plate of the present invention, the method includes: a first step for forming a cooling medium passage forming groove on each joining surface of a plurality of metal plates; a second step for forming an anodic oxide film by anodizing joining surfaces of the metal plates; and a third step for integrally joining the plurality of metal plates with the plurality of metal plates stacked by a friction agitation joining method. With this method, it is possible to effectively manufacture a cooling plate having the aforementioned features according to the present invention. Furthermore, since the anodizing processing is executed before the friction agitation joining, the anodic oxide film can be formed even at the details of the joining surfaces of the metal plates. Thus, the reliability of corrosion prevention at the joining surfaces of the metal plates can be enhanced, which enables to manufacture a high-performance cooling plate. Furthermore, since the joining of metal plates is performed by a friction agitation joining, the metal plates can be joined without deteriorating the previously formed anodic oxide film during the joining. Therefore, the aforementioned excellent corrosion resisting effects can be maintained sufficiently, which enables to manufacture a cooling plate excellent in durability and long in life.
Other objects and the features will be apparent from the following detailed description of the present invention with reference to the attached drawings.